Lamellarin family

A method for the direct C3 arylation of pyrroles 68 was developed with the goal of achieving the total synthesis of the lamellarin family of natural products 71. This -selective C-H arylation of pyrroles has a broad scope and is amenable to complex molecule synthesis (14JA13226). 

Another interesting investigation of the use of microwave irradiation for the synthesis of alkaloids was recently reported by M. Alvarez et al., where the authors investigated a modular total synthesis of Lamellarin D [93]. After 20 years of the first isolation of this compound from the marine prosobranch mollusk Lamellaria sp, this family currently comprises more than 30 members, isolated from various natural sources. With its recent identification as... 

Both AgOTf and AgSbF6 (10mol%) were the best catalysts for this transformation, and the reaction was conducted in the presence of an hindered base, 2,6-di-tert-butyl-4-methylpyridine (DTBMP). The azomethine ylide CC intermediate has been identified in a test reaction in the absence of DMAD, via mass spectrometry. The scope and limitations have been thoroughly studied for reaching pyrroloisoquinoline scaffold, which is a substructure of the lamellarin alkaloid family. 

Lamellarins O and P displayed a double family of signals corresponding to the aromatic carbon ortho to the phenolic functions, presumably due to the restricted rotation that generates chirality in these molecules <94AJC1919>. 

Using another approach, starting from the pyrrole core <04TL0000> syntheses of lamellarins Q and O were also achieved. In this work, the methyl A -(triisopropylsilyl)-3,4-dibromopyrrole-2-carboxylate 102 was used as the initial scaffold. Banwell et al. <97CC207> used the dibromopyrrole 102 in an elegant convergent synthesis of several compounds from this family of marine alkaloids (shown above). 

Bailly, C., (2004). Lamellarins, from A to Z A family of anticancer marine pyrrole alkaloids. Curr. Med. Chem. Anti-Cancer Agents 4, 363-378. 

With more than 350 original structures, almost all of which contain nitrogen, Didemnidae may be regarded as the richest family of the class Ascidiacea, with several molecules that are undergoing clinical trials for their antiviral and anti-tumor activity. Most of the structures isolated from Didemnidae derive from only three genera, Didemnum, Trididemnum and Lissoclinum, which each contain families of active substances (didemnins, eudis-tomins, lamellarins, lissoclinamides and Hssodimides). Table 28.3 shows the main types of structure encountered in the main genera of the order. 

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